In most computer graphics display devices in use today, color graphical images to be displayed must be in either (i) a 4-band, interleaved format in which four contiguous data components specify four respective components of a single pixel of the graphical image or (ii) in a 3- or 4-band planar format in which each band of respective pixels are stored separately. For example, the interleaved format can include four contiguous bytes of data which specify red, green, and blue components, respectively, of a single pixel. Similarly, the planar format can include data representing all red components of the pixels of a graphical image stored contiguously in a first buffer, data representing all green components of the pixels stored contiguously in a first buffer, and data representing all blue components of the pixels stored contiguously in a first buffer.
It is frequently desirable to convert a graphical image between interleaved and planar formats. It is common for graphical images produced today to include approximately one million pixels. For example, common sizes for graphical images include rectangular grids of 1024-by-768 pixels or 1280-by-1024 pixels, i.e., 786,432 and 1,310,720 pixels, respectively. To produce three separate buffers of respective bands of a graphical image from a single buffer containing a three-band graphical image in one conventional technique requires (i) approximately 750,000 read operations to read the pixels in the interleaved format, (ii) approximately two million shift operations and 8,250,000 logical operations to separate the respective components of each pixel, and (iii) approximately 750,000 write operations to store each band of each pixel in a respective single-band buffer.
Because of the significant computer system resources required for such graphical image reformatting, a need persists in the industry for ever increasing efficiency in conversion of graphical images from a single buffer of multiple bands of the graphical image to multiple buffers of respective single bands of the graphical image.